If the sealer is a very light thin smear, try some WD40 sprayed onto a rag, and wiped a few times. then try and roll the adhesive off with your thumb, neither will damage your paint, if it was baked and is now fully cured. If this doesn't do the trick, then you would be better off taking the car back to your painter first, for advice on removal, before contacting the screen fitter
Thom